(1) Field of the Invention
The present invention relates to the interconnection of electronic circuits and components. More specifically, this invention is directed to electrical conductors and particularly bus bars for interconnecting preselected terminal posts on terminal blocks, back planes, card edge connectors and circuit boards. Accordingly, the general objects of the present invention are to provide novel and improved articles of such character.
(2) Description of the Prior Art
In many types of electronic equipment, for example computers and electronic telephone switching systems, it is standard practice to mount components such as integrated circuits, transistors, and passive circuit elements on circuit boards which are received in card edge connectors. These connectors are provided, on one side, with terminal posts to which circuits on the board are electrically connected via "printed" connectors on the circuit boards and contacts on the connectors. The terminal posts, which are oriented transversely to the plane of the connector and often referred to as "wire wrap" pins, are used to establish interconnection between and for applying power to various circuits in the equipment.
It is known in the art to interconnect terminal posts on card edge connectors; and also on terminal blocks, back planes and circuit boards; through the use of push-on bus bars. Such push-on bus bars include a conductive member which is spring loaded against the terminal posts. Examples of prior art push-on bus bars may be found in U.S. Pat. Nos. 3,448,620; 3,582,864 and 3,829,818. With the exception of the bus bar of U.S. Pat. No. 3,829,818, which is assigned to the assignee of the present invention, the prior art push-on type bus bars have been characterized by one or more electrical or mechanical deficiencies. These deficiencies include unreliable contact between the pin or post and bus bar connector, high push-on forces which necessitated the use of special installation tools and/or awkward and time consuming hand insertion, and a sliding contact between the terminal pin or post and a sharp edge on the bus bar conductor which resulted in the scraping of the pins during bus bar insertion. The scraping of the pins often caused flaking of conductive material from the pins with the resultant contamination of adjacent circuits. Further disadvantages of prior art push-on type bus bars included distortion of the contacts or the contact surfaces on the bus bar, and in some cases also distortion of the pins; such distortion preventing removal and reinsertion and thus precluding reuse of the bus bars. Additionally, isolation or insulation of terminal pins which were not to be "commoned" by the bus bar was often awkward and time consuming and only one circuit program could be accomplished with a given bus bar. With regard to the programmability of the bus bar, it is highly desirable to afford the ultimate user of the device the option of selecting those terminal posts in a linear array which are not to be interconnected by a bus bar which extends along such array. As a further deficiency of many prior art push-on bus bars, these devices have been characterized by very limited current carrying capability and thus limited utility.